vy s pac series2 poor fuel economy

[jdcasagrande]

Hi, i was wondering if anyone was experiencing poor fuel economy with there VY holden s pac or anyone with the ecotec V6 engine?

This is the first supercharged vehicle i have ever owned, so im not sure if thats why the car drinks a lot of petrol, however prior to servicing the car i was getting 16L/100km which consisted of mainly suburban driving, which got me to about 370km to a tank, after i replaced the oil filter, air filter, spark plugs (bosch), fuel filter, cleaned throttle body (carby cleaner), and finally reset the cars ECU i have managed to only scrape around 390km/100km and runs around a 13.8/100km currently driving like a grandma

The only 2 things i have not replaced are the 02 sensor and the leads. I thought the o2 sensor would be fine, because i have head if that goes on the car you would be getting around a 17 - 18L/100km mark.

The car runs smooth when it is warm, however on start it shakes and then comes smooth, and the engine pings very slightly while waiting at the lights.

Could it be the Leads?

[Jezza]

what sort of octane petrol you putting in?

[Dr HaxZaw]

spark plugs, leads, o2 sensors

if that doesnt fix it possible try new coil packs and DFI module

[jdcasagrande]

I am running standard unleaded. But I have run a full tank of premium not too long ago, what kinda fuel economy do you blokes get?

Also I do notice the cars running rich, because there's a strong petrol fume smell coming from the exhaust

[vyseriesII]

I get around 12l/100km non supercharged around town(mildly modded). It appears you have consumption what i would call close to a v8 in that first figure. I use Bp 98 Always. Will never catch me putting in anything other than 98. What ever you do dont use E10. Did you clean your MAF sensor when you cleaned the throttle body? Use MAF cleaner from repco if you didn't. Don't use carby cleaner, it will eventually kill it. Also after you reset the ecu, give it about 200kms before you start to take any notice of the l/100km. I find it is always higher in the first few hundred kms and then settles to an average that seems more accurate. Make sure your brakes aren't locking on a little (siezed piston) and check your tyre pressure. Otherwise it comes down to what sort of driving you do eg. Heavy traffic stop starting you will always use a bit more than if you had more cruise driving conditions. Check your o2 sensors as stated above. I assume you have standard diff gearing? If idle is hunting or rough, make sure the IAC (Idle air control) is still working correctly in the throttle body.

[jdcasagrande]

thank you vyseries2 thats was really helpful advise, the driving i do in mainly in very little traffic, i drive a lot of backstreets to avoid traffic and i am currently running nulon fuel injector cleaner in my car aswell. I was unsure where the MAF sensor was located, is the MAF sensor the small filiments that are located in the steel bracket in the pipe just after the air filter box?

O2 sensor and leads are basically the next 2 things i am going to replace in the next week on my car after i clean the maf sensor.

[vyseriesII]

No worries Jd. MAF sensor in the device midway(usually) along your intake from the air box to the throttle body. Just unplug and take it out and give it a spray with the cleaner from both directions. Allow to dry before pluging back in

[jdcasagrande]

ok cheers, i will definitely clean that

[Sean880]

Hi, i was wondering if anyone was experiencing poor fuel economy with there VY holden s pac or anyone with the ecotec V6 engine?

This is the first supercharged vehicle i have ever owned, so im not sure if thats why the car drinks a lot of petrol, however prior to servicing the car i was getting 16L/100km which consisted of mainly suburban driving, which got me to about 370km to a tank, after i replaced the oil filter, air filter, spark plugs (bosch), fuel filter, cleaned throttle body (carby cleaner), and finally reset the cars ECU i have managed to only scrape around 390km/100km and runs around a 13.8/100km currently driving like a grandma

Could it be the Leads?

1. About 14 - 16 litres per 100 km is pretty normal for a supercharged V6 in city traffic running especially with lots of stopping and starting in typical Melborne traffic conditions.

2. The engine should not shake on start up.

3. You should run it on 95 RON premium not on regular unleaded. I get better fuel economy using 95 premium and you should not get any detonation/pinging that you have mentioned if you use premium fuel.

4. Take the car on a highway run and check the consumption sitting on around 100 kph. You should be getting between about 8 and 9 litres per 100 km on the flat. It should drop below 8 litres per 100 km at a steady 90 kph.

5. Add a bottle of nulon Fuel Injector Cleaner in the fuel tank with a full tank of fuel every 6 or 9 months.

6. Use a 10W/30 engine oil.

IMHO you will not get great fuel consumption economy in a VY commodore V6 in "city running" in MEL or SYD traffic. It's a relatively heavy car (over 1500 kgs) with a 3.8 litre motor and that is not a formula for good city fuel economy in normal city driving conditions, especially when you add in the S/Charger. A little less fuel economy is the trade off for the responsive supercharged engine which, in my opinion, is well worth it. At the end of the day one factor is individual driving style and how you use the right foot.

Overall the V6 VYs are very good cars which are practical, offer value for money and are relatively economical to run and service.

HOW MANY KMS HAS YOUR CAR LOGGED UP?

[jdcasagrande]

The cars done 133,000km and is in very good condition, and yes the petrol is totally worth the car
Would you recommend getting a tune done by holden? Are these tunes pricey?

[RiCeY]

Holden dont do any tuning apart from standard tunes which you most likely already have.

[jdcasagrande]

hi guys, just to let you know, ive solved the issue with high fuel usage.

I reason my car was using so much fuel was because it was missing a vacuum plug which sits below the supercharger, this was causing the car to over compenate in idle to prevent the car from stalling. I also have a leak in the inlet manifold and had a large amount of rust built up on my discs, a combination of this caused my high fuel consumption.

i now get around 11L/100km on highway driving, and 14L/100km on city driving, this is a big difference.

thanks for all your input

regards

Justin

[RiCeY]

lol @ rusty discs causing high fuel consumption!

[jdcasagrande]

apparently it was causing drag from the constant rubbing of the brake pads......

[RiCeY]

Umm no, the rust would be gone after a few applications of the brakes unless they were so badly rusted they shouldnt even be on the car.

[jdcasagrande]

haha ok no then.......in a perfect world technically yes the brakes should take the rust off, but as this aint a perfect world my friend in this case it didn't, it had an excess build up of rust and i got no idea how it got so bad. like i said it probly wasn't the initial cause of the poor fuel economy, but there was drag caused by the rust rubbing on the brakes (probly not enought to cause poor fuel economy), but enough to add the problem

[TMM]

If you stop from 60kmh it will remove any rust on the discs - yes even in a 'non perfect world'...